WO2002007640A1

WO2002007640A1 - Method for producing dental restoration

Info

Publication number: WO2002007640A1
Application number: PCT/CH2001/000448
Authority: WO
Inventors: Ulrich Mürrle; Pascal Streit; André Mostardi; Alexandre Fischer
Original assignee: Metalor Technologies S.A.
Priority date: 2000-07-21
Filing date: 2001-07-18
Publication date: 2002-01-31
Also published as: AU2001270417A1; EP1174095A1; EP1301143A1

Abstract

The invention concerns a method for producing a dental restoration (26) characterised in that it comprises the following successive steps: obtaining a die (16) of the stump of the tooth to be restored in refractory coating; applying on said die a piece remodelling (18) the tooth comprising a mixture of a refractory powder and a dispersion liquid; fixing on the remodelling piece (18) a metal foil (20) with a melting point lower than that of the refractory powder; coating the piece in a refractory coat (24), and curing the whole assembly at a temperature (T1) higher than the melting point of the foil but lower than the melting point of the refractory powder for a sufficiently long time interval to allow the powder to infiltrate through the molten metal of the foil (20).

Description

METHOD FOR CARRYING OUT A DENTAL RECONSTRUCTION

The present invention relates to dentistry. It relates, more particularly, to a process for producing a piece of dental reconstruction. Currently, the most commonly used technique for making a dental reconstruction is that of lost wax casting. More specifically, from the dentist's impression, the technician makes a plaster or resin replica of the stump to be reconstructed, then reshapes the tooth using wax applied to the replica. The piece of wax is then immersed in a refractory coating in the liquid state, the cooking of which allows the removal of the wax. A non-precious, semi-precious or precious reconstruction alloy is then poured into the mold thus formed, after which it only remains to remove the coating and the sprues to obtain the reconstruction part and to work it. with a view to placing it in the mouth (polishing, placing a decorative composite or ceramic).

Another dental reconstruction technique, illustrated by documents US 5,909,612, US 4,661,071 and FR 2,702,649, consists in:

- obtain a replica of the stump of the tooth to be reconstructed in refractory lining, - apply to this replica a piece of tooth remodeling comprising a mixture of a refractory powder and a dispersion liquid,

- infiltrate the remodeling part using a molten metal, and

- remove the refractory lining. The present invention aims purely to provide an improved method of manufacturing a dental reconstruction, making it possible, almost à la carte, to produce a part whose composition and respective contents of non-precious, semi-precious and precious elements can be chosen. in a very large palette. To achieve this goal, the method according to the invention, of the type defined above, is characterized in that, according to a first embodiment, the infiltration step comprises the successive operations of:

- fixing on the remodeling part of a metallic straw having a melting point lower than that of the refractory powder,

- coating of the part in a refractory lining, and

baking the assembly at a temperature above the melting point of the straw but below the melting point of the refractory powder for a time long enough to allow the powder to infiltrate the molten metal of the straw.

According to a second embodiment, the infiltration step comprises the successive operations of:

first firing of the assembly at a temperature below the melting point of the refractory powder,

application of a metallic paste having a lower melting point than that of the refractory powder on the remodeling part, and

- Second baking of the assembly at a temperature higher than the melting point of said metallic paste but lower than the melting point of the refractory powder for a time long enough to allow the powder to infiltrate with the molten metal of the paste.

According to a third embodiment, the infiltration step comprises the successive operations of:

fixing on the remodeling part of a metallic straw having a melting point lower than that of the refractory powder, and - Second baking of the assembly at a temperature higher than the melting point of the straw but lower than the melting point of the refractory powder for a time long enough to allow the powder to infiltrate the molten metal of the straw. According to a fourth embodiment, the infiltration step comprises the successive operations of:

- extension of the remodeling part by a pumping tab,

bringing said tongue into contact with a metallic straw having a melting point lower than that of the refractory powder, and

According to a fifth embodiment, the infiltration step comprises the successive operations of:

- extension of the reshaping part by a pumping tab, - first firing of the assembly at a temperature below the melting point of the refractory powder,

- bringing said tongue into contact with a metallic straw having a melting point lower than that of the refractory powder, and - second firing of the assembly at a temperature higher than the melting point of the straw but lower than the melting point of the refractory powder for a time long enough to allow infiltration of the powder by the molten metal of the straw.

Preferably, the straw or the metallic paste contains at least one metal chosen from gold, cobalt, iron, aluminum and magnesium and, optionally in addition, at least one metal chosen from silver, chromium. , the zinc, copper, gallium, titanium, zirconium, retain, indium, silicon and tantalum.

Advantageously, the refractory powder can comprise at least one carbonitride of a metal chosen from titanium, tantalum, zirconium and silicon. Furthermore, the refractory powder grains preferably have an average size of less than 100 μm but, advantageously, less than 50 μm.

The invention will be better understood on reading the description which follows, made with reference to the appended drawing in which: - Figure 1 illustrates the first operations of the process; and

- Figures 2 to 6 show the following operations for five different modes of implementation of the invention.

Firstly, reference is made to FIG. 1, which illustrates in 1a the first operation carried out by the technician to manufacture a dental reconstruction. This operation consists in making a replica 10, in plaster or resin, of the impression made by the dentist in the patient's mouth.

Then, as shown in 1b, the replica 10 of the tooth stump to be reconstructed is coated in a silicone block 12 before being extracted therefrom to form a mold into which is poured a liquid refractory coating 14, as shown in 1c. This coating can be of any type known to those skilled in the art, such as, for example, those sold under the references Multivest MS 24, Heravest Speed and Univest Rapid.

After taking the coating and removing the silicone mold 12, the technician has a replica 16 of the stump of the tooth in refractory lining, as shown in 1d.

The next step of the process, illustrated in 1e, is the application on the replica in refractory lining 16 and its modeling, in any desired form, of a paste 18 produced by the mixture of a refractory powder and a liquid of dispersion. It is a metallic or ceramic powder whose grains have an average dimension of less than 100 μm but, preferably, less than 50 μm.

When the powder is metallic, it is formed from grains of an element chosen from iridium, ruthenium, rhodium, rhenium, osmium, cobalt, tungsten, molybdenum, niobium, tantalum, titanium, platinum and palladium. It can also consist of a mixture of grains of the aforementioned elements with each other or with other elements, such as gold, silver, zinc, indium and tin. The powder can also be a powder of an alloy based on the same metals. When the powder is ceramic, it is formed of grains of either an oxide of a metal chosen from aluminum, zirconium, titanium, magnesium and silicon, or a nitride of a metal chosen from titanium, tantalum, zirconium and silicon, or a carbide of a metal chosen from titanium, tantalum, tungsten, molybdenum, zirconium and silicon, or a carbonitride of a metal chosen from titanium, tantalum, zirconium and silicon, or finally several of these components.

The dispersion liquid advantageously consists of a solvent, such as water or terpineol, and an organic binder which can be removed by heating at a temperature above 600 ° C., such as methyl cellulose or ethyl. cellulose. The liquid can also contain only an organic binder, such as wax or polyethylene glycol.

Typically, by way of nonlimiting example, the remodeling paste 18 is a mixture comprising:

- 30 to 40% by volume, either of a mixture comprising 70% by weight of iridium powder and 30% by weight of gold powder, or 100% by weight of molybdenum or tungsten powder; and

- 70 to 60% by volume of a solution containing 99% by weight of water and 1% by weight of methyl cellulose.

FIG. 2 illustrates the continuation of the operations of the method according to a first advantageous embodiment of the invention. The operation shown in 2a is the installation, at the top of the reshaping part 18, of a metallic straw 20 having a melting point lower than that of part 18 of, typically more than 100 ° C. The straw 20 is glued to the part using a paste similar to the remodeling paste 18 previously described.

The straw 20 is advantageously made of a metal chosen from gold, cobalt, iron, aluminum and magnesium or an alloy based on these metals. It can also contain additives chosen from silver, chromium, zinc, copper, gallium, titanium, zirconium, tin, indium, silicon and tantalum.

Typically, when the remodeling dough has the composition given above by way of example, the straw 20 is an alloy containing 90% by weight of gold and 10% by weight of silver.

After drying, when only the refractory powder remains, which thus forms a porous skeleton, the next step, illustrated by FIG. 2b, is the coating of the assembly in a liquid refractory coating 24 similar to the coating 16 previously described.

When the coating 24 has solidified, as illustrated in FIG. 2c, the whole is cooked at a temperature T1 higher than the melting point of the straw 20 but lower than the melting point of the part 18 for a time long enough to allow the infiltration, by capillary action, of this porous skeleton by the molten metal of the straw.

Typically, when the remodeling paste and the straw have the compositions given above, the baking is done at 1150 ° C. for 20 minutes in an air laboratory oven, such as that sold under the reference Kavo EWL 5646 (Kavo, DE), or an oven for firing dental ceramic in air or under vacuum, such as that sold under the reference Programat P95 (Ivoclar, Ll).

It then only remains to allow the part to cool and then to remove the refractory linings 16 and 24 as well as any residue from the straw 20. which remains is a reconstruction part 26, shown in FIG. 2d, of the same shape as the part 18, which can be worked, in a conventional manner, with a view to placing it in the mouth.

The refractory powder forming the skeleton of this reconstruction part 26 has a porosity which can, depending on the morphology and size distribution of the grains of the powders, be between about 40 and 70%, that is to say that 40 to 70 % of the volume is occupied by the infiltrated metal and therefore that respectively the remaining 60 to 30% is occupied by the powder. This proportion can however be modified by mixing with the refractory powder a metallic powder having a composition similar to that of the straw. In this case, during cooking, this metallic powder melts and combines with the infiltrated metal, so that it is then possible to obtain a reconstruction containing, typically, from 15 to 70% of the volume of refractory powder and, respectively, from 85 to 30% of the volume of metal having the composition of the infiltration metal.

It is thus possible to carry out a dental reconstruction, the composition and the respective contents of non-precious, semi-precious and precious elements, can be chosen almost à la carte from a wide range. Reference will now be made to FIG. 3 which, according to a second advantageous embodiment of the invention, shows the operations carried out after the application on the replica 16 of a remodeling paste 18 based on refractory powder, such as illustrated in Figure 1e.

In this case, the part is, first of all, as shown in FIG. 3a, baked at a temperature To lower than the melting point of the dough 18 for a time long enough to transform it into a porous skeleton.

As illustrated in FIG. 3b, the part 18 is then covered with a second layer of metallic paste 28 having a composition identical to that of the straw 20 used in the first embodiment. The piece then undergoes, as illustrated in FIG. 3c, a second baking at a temperature T1 higher than the melting point of the paste 28 but lower than the melting point of the porous skeleton 18 for a time long enough to allow its infiltration by capillarity. This operation is typically carried out under conditions identical to those of the operation illustrated in FIG. 2b. Preferably, the temperature T1 of this second cooking is more than 100 ° C. lower than that To of the first.

There is then only to allow the part to cool and then to remove the refractory lining 16 by breaking it with a hammer. What remains is a reconstruction part 30, represented in FIG. 3d, of the same shape as the part 18, which can be worked, in a conventional manner, with a view to placing it in the mouth.

FIG. 4 illustrates a third embodiment of the method according to the invention, quite similar to that of FIG. 3. In this case, after the first cooking operation of FIG. 4a, identical to that of FIG. 3a, we puts in place at the top of the reshaping part 18, as illustrated by FIG. 4b, a metal straw 32 identical to the straw 20 of FIG. 2a. The part then undergoes, as illustrated in FIG. 4c, a second firing at a temperature T1 higher than the melting point of the straw 32 but lower than the melting point of the porous skeleton 18 for a time long enough to allow its infiltration by capillarity. . This operation is carried out under conditions identical to those of the operation illustrated in FIG. 3c.

After the part has cooled, the refractory lining 16 is removed as well as any residue from the straw 32, to leave a reconstruction part 34, shown in FIG. 4d, of the same shape as the part According to a fourth advantageous embodiment of the invention, FIG. 5 shows the operations carried out after application to the replica 16 of a remodeling paste 18 based on refractory powder, as illustrated by FIG. 1e. The first operation, represented by FIG. 5a, is the extension of the dough 18 by a pumping tongue 36 of the same composition as it.

The part is then deposited in a melting tank 38, shown in FIG. 5b, by bringing the tongue 36 into contact with a metal straw 40 of the same composition as the straw 20 in FIG. 2a. The following operation, illustrated by FIG. 5c, is the firing of the assembly at a temperature T1 higher than the melting point of the straw 40 but lower than the melting point of the porous skeleton 18 for a time long enough to allow its infiltration by capillarity through the pumping tongue 36. After cooling of the part, the last operation consists in eliminating the refractory lining 16 as well as the tongue 36 and any residue from the straw 40 to leave a reconstruction part 42, shown in FIG. FIG. 5d, of the same shape as the part 18.

Finally, reference will be made to FIG. 6 which represents, according to a fifth advantageous embodiment of the invention, the operations carried out after the application on the replica 16 of a remodeling paste 18 based on powder refractory, as illustrated in Figure 1e.

The first operation, shown in Figure 6a, is identical to that of Figure 5a. The following operation, represented in FIG. 6b and identical to the operations in FIGS. 3a and 4a, consists in baking the part at a temperature To lower than the melting point of the dough 18 for a time long enough to transform it into a porous skeleton. The following two operations, illustrated by FIGS. 6c and 6d, are identical to the operations in FIGS. 5b and 5c, the temperature T1 of the second cooking being, as in the case of FIG. 3c, more than 100 ° C lower than that To of the first.

Finally, after the part has cooled, the last operation consists in eliminating the refractory lining 16 as well as the tongue 36 and any residue from the straw 40 to leave a reconstruction part 44, shown in FIG. 6d, of the same shape as the Exhibit 18.

Claims

1. Method for making a dental reconstruction, comprising the successive steps of:

- obtaining a replica (16) of the tooth stump to be reconstructed in refractory lining,

- application to said replica of a part of reshaping (18) of the tooth comprising a mixture of a refractory powder and a dispersion liquid,

- infiltration of said part by means of a molten metal (20), and

- elimination of the refractory lining (16), characterized in that the infiltration step comprises the successive operations of:

- fixing on the remodeling part (18) of a metallic straw (20) having a melting point lower than that of the refractory powder,

- coating of the part in a refractory lining (24), and

baking the assembly at a temperature (T1) higher than the melting point of the straw but lower than the melting point of the refractory powder for a time long enough to allow the powder to infiltrate the molten metal of the straw (20 ).

2. Method for carrying out a dental reconstruction, comprising the successive stages of:

- infiltration of said part (18) by means of a molten metal, and

- elimination of the refractory lining (16), characterized in that the infiltration step comprises the successive operations of: first firing of the assembly at a temperature (To) lower than the melting point of the refractory powder,

fixing on the remodeling part (18) of a metallic straw (32) having a melting point lower than that of the refractory powder, and

- second baking of the assembly at a temperature (T1) above the melting point of the straw but below the melting point of the refractory powder for a time long enough to allow the powder to infiltrate the molten metal of the straw ( 32).

3. Method for carrying out a dental reconstruction, comprising the successive stages of:

- infiltration of said part (18) by means of a molten metal, and

- extension of the remodeling part (18) by a pumping tongue (36),

bringing said tongue into contact with a metallic straw (40) having a melting point lower than that of the refractory powder, and

baking the assembly at a temperature (T1) higher than the melting point of the straw but below the melting point of the refractory powder for a time long enough to allow the powder to infiltrate the molten metal of the straw (40 ).

4. Method for carrying out a dental reconstruction, comprising the successive stages of:

- infiltration of said part (18) by means of a molten metal, and

- extension of the remodeling part (18) by a pumping tongue (36),

first firing of the assembly at a temperature (To) below the melting point of the refractory powder,

- second baking of the assembly at a temperature (T1) above the melting point of the straw but below the melting point of the refractory powder for a time long enough to allow the powder to infiltrate the molten metal of the straw ( 40).

5. Method according to one of claims 1 to 4, characterized in that the straw (20, 32, 40) or the metallic paste (28) contains at least one metal chosen from gold, cobalt, iron, aluminum and magnesium.

6. Method according to claim 5, characterized in that the straw (20, 32, 40) or the metallic paste (28) additionally contains at least one metal chosen from silver, chromium, zinc, copper, gallium, titanium, zirconium, tin, indium, silicon and tantalum.

7. Method according to one of claims 1 to 4, characterized in that said refractory powder comprises grains of at least one carbonitride of a metal chosen from titanium, tantalum, zirconium and silicon.

8. Method according to claim 7, characterized in that the grains of said refractory powder have an average dimension of less than 100 μm.